Charge forming device



Aug. 14, 1934., w TEETER 1,970,026

CHARGE FORMING DEVICE 1 Filed May 51, 1930 IQ IaA firm... Illll s51, qgmoulm x 1M.

Patented Aug. 14, 1%34 UNITED res FATE 1,979,025 F FICE CHARGE FDR/MINGDEVICE ration, Detroit, Mich.

ware

, a corporation of Dela- Application May 31, 1930, Serial No. 457,821

17 Claims.

This invention relates to carburetors for internal combustion engines,and more particularly to carburetors which comprise a plurality ofprimary mixture passages which are adapted to deliver a primary mixtureof fuel and air to a plurality of secondary mixing chambers in which theprimary mixture is adapted to be mixed with additional air under certainoperating conditions.

A carburetor of this character is described in the copending applicationof Wilford H. Teeter, Serial No. 288,685, filed June 2'1, 1928, whichhas resulted in Patent No. 1,904,634, granted April 18, 1933, and thepresent invention is illustrated as embodied in a carburetor of thegeneral construction disclosed in such application.

It is the principal object of this invention to provide improved meansfor automatically controlling the mixture proportions during operationunder varying conditions and at varying speeds. More particularly, it isan object of this invention to provide means for automatically forming amixture of substantially constant proportions and for preventing theleaning of the mixture subsequent to the opening of the secondary airvalve.

It is a further object of the invention to provide means for securingthe above results, which is simple in construction and free from movingparts.

In some carburetors of this type it has been observed that subsequent tothe opening of the secondary air valve there is a tendency for themixture to become too lean and various means have been provided tocorrect this tendency, generally a secondary fuel inlet which iscontrolled by a fuel valve normally closed and adapted to be openedeither substantially simultaneously with the opening of the secondaryair valve, or subsequent to the opening of such valve. Difficulty beenexperienced in synchronizing the operation of the various moving partsso that it has proved difficult to provide a mixture of the desiredproportions.

According to this invention, the additional fuel inlet has beeneliminated and means are provided to increase the suction effective on asingle "ael inlet, as the quantity of air is increased, after theopening of the secondary air valve as well as before, so that theincrease in fuel and air is at substantially the same rate throughoutthe operating range. Up to a predetermined throttle position, thesuction at the fuel inlet is the static suction of the main air chamber,but when the throttle is opened further, the suction at the fuel inletis modified by communicating the eifect of the velocity head thereto,the suction thus being increased to some extent in the higher speedrange.

Further objects and advantages of the present invention will be apparentfrom the following dscription, reference being had to the accompanyingdrawing wherein a preferred embodiment of one form of the presentinvention is clearly shown.

In the drawing:

Fig. 1 is a vertical section through a carburetor unit forming a part ofthe charge forming device in which the present invention is embodied.

Figs. 2, 3 and 4 are sections on the lines 2-2, 33 and l4 respectively.

Fig. 5 is a detail view of a suitable operating connection between thethrottle and an associated valve.

Referring to the drawing and particularly to Fig. l, the referencenumeral 20 indicates the main housing of the carburetor which isprovided with a flange 22 adapted to be secured to an intake manifold ofthe type shown in the above mentioned application and which is notdisclosed herein for the purpose of simplifying the disclosure. Acasting 24 is positioned just below the main housing and is securedthereto in any desirable manner. Various fuel supply passages and otherchambers are formed in this casting. An air inlet coupling 26 is adaptedto be secured in position in an opening in the upper wall of the mainhousing by screws 28 and a float bowl 30 is held tight against anannular shoulder 32 on the casting 24 by a screw 34, screwed into saidcasting, suitable gaskets being provided to prevent leakage of the fuel.Fuel is supplied to the float bowl from the main source of supplythrough a passage which is not shown and the flow is controlled by afloat 36 which operates in the usual manner to maintain a constant levelof fuel in the bowl.

Fuel flows from the bowl 30 to a plurality of primary mixing chambers38, the construction of which is described more fully hereinafter. Thefuel conduit between the-fuel bowl and the primary mixing chamberscomprises an angular fuel passage 40, which communicates at its upperend with a horizontal fuel canal .2 connecting with three horizontalpassages 43, each of which connects with one of three vertical passagesto, which are connected at their upper ends with horizontal passages 46.Passages 46, at their delivery ends, are restricted, as indicated at 48,and supply fuel to a horizontal passage 50, which communicates withthree vertical passages 52, at the lower ends of which are providedthree fuel feeding orifices 54, each of which supplies fuel to one ofthe primary mixing chambers 38. The static suction of the air chamber,as more fully described hereinafter, is maintained at the fuel inletorifices 48 up to a predetermined throttle opening, so that no velocityhead is present at these orifices under such operating conditions. Aswill be explained more fully hereinafter, the efiect of a velocitysuction is communicated to the inlets 48 when the throttle is openingbeyond the predetermined position referred to. A calibrated plug 56 isprovided at the intake end of the fuel delivery passage 40 to regulatethe flow of fuel therethrough, while the restrictions 54 regulate theflow from each fuel feeding orifice into the primary mixing chamber withwhich it is associated.

The primary mixing chambers 38 comprise the vertical intake ends ofprimary mixture passages 58, which are parallel to each other andrelativ ly close together, as indicated in Fig. 5. When the carburetoris attached to the manifold, these passages are adapted to register withconduits which convey the primary mixture to secondary mixing chambersformed in the manifold and constructed in the manner fully disclosed inthe application above referred to. A single throttle valve 60 controlsthe flow through the primary mixture passages and extends across all ofsaid passages, being provided with grooves 62 which register with themixture passages.

Air is admitted to the carburetor through the inlet coupling 26 and iscontrolled by a main air valve 64, normally held against the seat 66 bya spring 68, received between the valve and a flange '70, projectingfrom a sleeve 72, slidably mounted on a sleeve '74, fixed in the mainhousing and guiding the stem '76 on which the air valve is secured. Tofacilitate starting, the flange 70 is lifted by an arm 78, which extendsthereunder and is operated at will by the operator of the vehicle, tohold the valve 64 closed, as fully disclosed in the above mentionedapplication. Sufiicient air to carry the starting fuel from the nozzlesto the intake ports is admitted through an orifice in the housing as isalso described in said above mentioned application.

The valve 64 admits air to a main air chamber 80, from which air flowsdirectly into the primary mixing chambers 88 and to the secondary mixingchambers through a passage 82, which is adapted to connect with theinlet of the manifold when the carburetor unit is secured thereto. Thefiow through this passage is controlled by manually and suction operatedvalves 84 and 86 secured to shafts 88 and 90, journalled in the mainhousing.

The operating connections for the throttle and the valve 84 form no partof this invention. It is regarded as sufficient for the purposes of thisdisclosure to state that the primary throttle is connected to the valve84 by an adjustable lost motion connection, which permits apredetermined movement of the primary throttle indeendent of said valve84 and is generally adjusted so that the primary throttle is movablewithout accompanying movement of the valve 84 until the former reaches aposition corresponding to a vehicular speed of approximately 15 to 20miles per hour on the level. On further opening of the primary throttle,the valve 84 is moved simultaneously therewith. Such a lost motionconnection is illustrated in Fig. 5, which connection comprises a pin108 secured to an arm 110 on shaft 90 of valve 84 and projecting througha slot 112 in a link 114 secured to an arm 116 on throttle 60. The valve86 is opened by engine suction and opens only after the valve 84 isopened.

Any increase of suction in the main air chambar is accompanied by anopening movement of the valve 64, which movement is retarded to preventiiuttering of the valve and to prevent leaning of the mixture by adashpot comprising a cylinder 92 and a piston 94 slidable therein, andsecured to the end of the valve stem '76. The details of construction ofthe dashpot are unimportant so far as the present invention is concernedand that disclosed is of the same form as described in detail inapplication Serial No. 288,685.

The passage 96 constitutes a fuel delivery passage from the cylinder,which forms a fuel pump, to the primary mixture passages 58, into whichfuel is injected by the pump on every opening of the main air valvefollowing an opening movement of the throttle. At the same time the pumpis effective, the opening of the suction operated valve 86 istemporarily retarded to restrict the admission of air through thesecondary air passage for reasons which are fully set forth inapplication Serial No. 288,685 in which the pump and the means forretarding the opening of the valve 86 are also fully described.

It will be understood that the valve 86 may be in the position in whichit is shown herein as indicated at 98 in Fig. 2 for a purpose to belater described, or the secondary air passage 82 may be somewhatlengthened and the valve 86 placed in a position posterior to the valve84 as in certain earlier devices, for instance that shown in thecopending application of Wilford H. Teeter et al., Serial No. 288,683,filed June 27, 1928.

Communicating with the middle one of vertical passages 52, as shown inFig. 2, is a tube 100, extending upwardly into the air chamber where itis bent to project horizontally into the secondary air passage 82, theposterior end of the tube being received within a small Venturi tube102, secured in position against the lower wall of the secondary airpassage by a screw 104, screwed into the main housing. The tube 106terminates adjacent the point of greatest restriction in the mixturetube and an inlet orifice 105 is provided in the tube intermediate itsends. The admission of air through the tube 100 and the communication ofsuction therethrough to the passage 52 controls the amount of fuelthrough the orifices 48, thus regulating the mixture proportions. Plugs108 close the two outer vertical passages so that the tube 100 admitsair to all of said passages 52.

The operation of this tube and its function in controlling the mixtureproportions is substantially as follows: At all times and under alloperating conditions when the valves in the secondary air passage 82 areclosed, air is admitted to the passages 52 through the open end of thetube 100 and the orifice 106. The inside area of the tube is greaterthan the combin d areas of the outlets 54, therefore, the air must movethrough the passages 52 at so low a velocity that no velocity head iscreated at the orifices 48 prior to the opening of the valves 84 and 86,and the suction maintained at such orifices is substantially the staticsuction of the air chamber 80. Subsequent to the opening of the valves84 and 86, the increase in the amount of air supplied to the intakeports on opening movement of the throttle is so rapid that there must bea corresponding increase in the amount of fuel supplied, and to effectsuch increase in fuel flow, the suction at the orifices 48 must beincreased more rapidly on opening of the throttle than was necessaryprior to the opening of the valves 84 and 86. This stepping up of therate of increase in fuel flow is accomplished by the Venturi tube 162,which creates a velocity suction at the end of the tube 100 subsequentto the opening of the valves 84 and 86, which is communicated throughthe tube to the orifices 48.

The efiect of the velocity head is modified to some extent by theadmission of air through the orifice 106, which may be made of whateversize is suitable to give exactly the increase desired, or the hole maybe omitted altogether if it be desired to communicate the velocity headunmodified to the fuel feeding orifices 48.

In the embodiment shown in the drawing the suction which is actuallymaintained at the orifices 48 is greater than the static suction of theair chamber 80, but is less than the velocity suction created at the endof the tube 100, due to the modifying effect of the orifice 106 in thetube. Also, owing to the fact that the velocity suction within theVenturi tube 102 increases more rapidly than the static suction ofchamber 80, it will be apparent that the increase in suction at orifice48 on opening movement of the throttle is greater after the opening ofvalves 84 and 86 than before. The actual suction at the orifices 48after the venturi has begun to function might be said to be the sum ofthe suction efi'ects of the static suction of chamber and the velocitysuction of the venturi 102, being somewhere between these two suctions,the exact degree of suction depending on the relative sizes of thevarious parts.

While the form of embodiment of the present invention as hereindisclosed, constitutes a preferred form, it is to be understood thatother forms might be adopted, all coming within the scope of the claimswhich follow.

What is claimed is as follows:

1. A carburetor having in combination, a mixture passage, a fuel inletsupplying fuel to the mixture passage, an air inlet therefor, means foreffecting a flow of fuel from said fuel inlet by a suction substantiallyequal to the static suction within the carburetor until the throttle hasmade a predetermined opening movement, means for communicating theeffect of a velocity head to said fuel inlet when the throttle is openedto a greater degree, and means operated after said predetermined openingmovement of the throttle to render the second-mentioned means operative.

2. A carburetor comprising a primary mixture passage adapted to delivera primary mixture of air and fuel to a secondary mixing chamber, asecondary air passage adapted to supply air to be mixed with the primarymixture, a throttle, a fuel inlet for supplying fuel to said primarymixture passage, a main air chamber adapted to supply air to saidprimary mixture passage and secondary air passage, means forcommunicating substantially the static suction of the air chamber to thefuel inlet, normally ineffective means for communicating the velocitysuction of the secondary air passage to the fuel inlet, and means forrendering said last mentioned means effective after the throttle hasmade a predetermined opening movement.

3. A carburetor comprising a primary mixture passage adapted to delivera primary mixture of air and fuel to a secondary mixing chamber, asecondary air passage adapted to supply air to be mixed with the primarymixture, a fuel inlet for supplying fuel to said primary mixturepassage, a main air chamber adapted to supply air to said primarymixture passage and secondary air passage, normally ineffective meansfor communicating the velocity suction of the secondary air passage tothe fuel inlet, and a valve in said secondary air passage forcontrolling the effectiveness of said last mentioned means andregulating the flow of air through'said secondary air passage. i

4. A carburetor comprising a primary mixture passage adapted to delivera primary mixture of air and fuel to a secondary mixing chamber, asecondary air passage adapted to supply air to be mixed with the primarymixture, a fuel inlet for supplying fuel to said primary mixturepassage, a main air chamber adapted to supply air to said primarymixture passage and secondary air passage, normally ineffective meansfor communicating the velocity suction of the secondary air passage tothe fuel inlet, a valve in said secondary air passage adapted to rendersaid last mentioned means effective when said valve begins to open andadapted to be opened after a predetermined opening movement of the throttle.

5. A carburetor comprising a mixture passage, a fuel inlet supplyingfuel thereto, an air inlet therefor, a throttle, means, for creating asuction at said fuel inlet which increases as the throttle is opened,means for accelerating the rate of increase in suction at the fuel inletduring opening movements of the throttle under certain operatingconditions, and means operated after a predetermined movement of thethrottle to render the second-mentioned means operative.

6. A carburetor comprising, a primary mixture passage adapted to delivera primary mixture of air and fuel to a secondary mixing chamber, asecondary air passage adapted to supply air to be mixed with the primarymixture, a fuel inlet for supplying fuel to said primary mixturepassage, a main air chamber adapted to supply air to said primarymixture passage and secondary air passage, a throttle, a valve in thesecondary air passage, means for maintaining a suction at the fuel inletwhich increases as the throttle is opened, and means for acceleratingthe rate of increase of said suction after the valve in said secondaryair passage is open.

7. A carburetor comprising, a primary mixture passage adapted to delivera primary mixture of air and fuel to a secondary mixing chamber, asecondary air passage adapted to supply air to be mixed with the primarymixture, a fuel inlet for supplying fuel to said primary mixturepassage, a main air chamber adapted to supply air to said primarymixture passage and secondary air passage, and a tube communicating withthe fuel inlet, the main air chamber and the secondary air passage,whereby the suction of the air chamber is communicated to the fuel inletunder certain operating conditions and under other operating conditionsthe velocity suction of the secondary air passage becomes effeotive incontrolling the fuel flow.

8, A carburetor comprising, a primary mixture passage adapted to delivera primary mixture of air and fuel to a secondary mixing chamber, asecondary air passage adapted to supply air to be mixed with the primarymixture, a fuel inlet for supplying fuel to said primary mixturepassage, a main air chamber adapted to supply air to said primarymixture passage and secondary air passage, and a tube communicating withthe fuel inlet, the main air chamber and the secondary air passage,whereby the suction maintained at the fuel inlet is the compositesuction effect of the static suction of the main air chamber and thevelocity suction of the secondary air passage. V

9. A carburetor for internal combustion engines comprising a mixturepassage, a throttle regulating the flow therethrough, fuel and airinlets therefor, a tube communicating with the fuel inlet and operativeto control the suction effective on the fuel inlet, means foraccelerating the flow of air past the end of the tube to create avelocity suction, to be communicated through the tube to said fuel inletand a vent in said tube adapted to admit air to modify the effect of thevelocity suction.

10. A carburetor comprising a primary mixture passage adapted to delivera primary mixture of air and fuel to a secondary mixing chamber, asecondary air passage adapted to supply air to be mixed with the primarymixture, fuel and air inlets for supplying fuel and air to the primarymixture passage, a valve in said secondary air passage, a tubecommunicating with said fuel inlet and extending into said secondarymeans for accelerating the flow of air past the end of said tube whensaid valve is open, to create a velocity head at the end of the tube tobe communicated thereby to the fuel inlet and a vent in said tube tomodify the effect of the velocity suction on the fuel inlet.

11. A carburetor for internal combustion engines comprising a pluralityof primary mixture passages, fuel and air inlets for each of saidmixture passages, a secondary air passage adapted to supply air to bemixed with the primary mixture formed in each of said primary mixturepassages, an" air chamber for supplying air to all of said primarymixture passages and said secondary air passage and a passsge forcommunicating the suction of the air chamber and the secondary airpassage to all of the fuel in lets.

12. A carburetor, comprising, a primary mixture passage adapted todeliver a primary mixture of fuel and air to a secondary mixing chamber,a throttle, a secondary air passage adapted to supply air to saidsecondary mixing chamber to be mixed with the primary mixture of fueland air and operative only under certain conditions, a main air chamberadapted to supply air to the primary mixture passage, means operativeunder certain conditions for maintaining at the fuel inlet substantiallythe same suction as is maintained in the main air chamber, means forcreating a flow of air at high velocity in said secondary air passagewhen the latter is effective, and means for communicating the suction ofthe high velocity air current to the fuel inlet to modify the airchamber suction maintained at said fuel inlet.

13. A carburetor, comprising, a primary mixture passage adapted todeliver a primary mixture of fuel and air to a secondary mixing chamber,a throttle, a secondary air passage adapted to supply air to said'secondary mixing chamber to be mixed with the primary mixture of fueland air and operative only under certain conditions, a main air chamberadapted to supply air to the primary mixture passage, means operativeunder certain conditions for maintaining at'the fuel inlet substantiallythe same suction as is maintained in the main air-chamber, a Venturitube in said secondary air passage through which air flows at highvelocity when said secondary air passage is effective and means forcommunicating the suction maintained within the Venturi tube to the fuelinlet to modify the air chamber suction maintained at said fuel inlet.

14. A carburetor, comprising, a primary mixture passage adapted todeliver a primary mixture of fuel and air to a secondary mixing chamber,a throttle, a secondaryair passage adapted to supply air to saidsecondary mixing chamber to be mixed with the primary mixture of fueland air and operative only under certain conditions, a main air chamberadapted to supply air to the primary mixture passage, means operativeunder certain conditions for maintaining at the fuel inlet substantiallythe same suction as is maintained in the main air chamber, means forcreating a flow of air at high velocity in said secondary air passagewhen the latter is effective, and a conduit extending from the point ofhigh velocity air flow to the fuel inlet to communicate the velocitysuction created by said air flow to the fuel inlet to modify the effectof the air chamber suction.

15. A carburetor, comprising, a primary mixture passage adapted todeliver a primary mixture of fuel and air to a secondary mixing chamber,a throttle, a secondary air passage adapted to supply air to saidsecondary mixing chamber to be mixed with the primary mixture of fueland air and operative only under certain conditions, a main air chamberadapted to supply air to the primary mixture passage, means operativeunder certain conditions for maintaining at the fuel inlet substantiallythe same suction as is maintained in the main air chamber, means forcreating a flow of air at high velocity in said secondary air passagewhen the latter is effective, a conduit extending from the point of highvelocity air flow to the fuel inlet to communicate the velocity suctioncreated by said air flow to the fuel inlet to modify the effect of theair chamber suction and an orifice in the conduit to modify the eifectproduced at the fuel inlet.

16.. Acarburetor comprising a primary mixture pamage adapted to deliver.a primary mixture of air and fuel to a secondary mixing chamber, athrottle, a secondary air passage adapted to supply air to be mixed withthe primary mixture after a certain opening movement of the throttle, afuel inlet for supplying fuel to said primary mixture passage, a mainair chamber adapted to supply air to said primary mixture passage andsecondary air passage, means for communicating substantially the staticsuction of said air chamber to the fuel inlet when the secondary airpassage is ineffective and means for modifying this suction only afterthe secondary air passage has been rendered effective to supplyadditional air.

17. A carburetor comprising a primary mixture passage adapted to-delivera primary mixture of air and fuel;to a secondary mixing chamber, athrottle, a secondary air passage adapted to supply air to be mixed withthe primary mixture after a certain opening movement of the throttle, afuel inlet for supplying fuel to said primary mixture passage, a mainair chamber adapted to supply air to said primary mixture passage andsecondary air passage, means for communicating substantially the staticsuction of the air chamber to said fuel inlet when the secondary airpassage is ineffective and means for communicating the suction createdby the air passing through the secondary air passage to the fuel inletwhen this secondary air passage has been rendered effective to supplyadditional air.

WILFORD H. TEETER.

